Halogen containing high-pressure mercury vapor discharge lamp

ABSTRACT

A high-pressure mercury vapor discharge lamp including halide additions. The lamp comprises, next to mercury and a rare gas, one or more of the halogens iodine, bromine and chlorine and furthermore sodium, thallium and possibly indium. The lamp comprises calcium in the form of calcium halide which emits in a broad band in the red part of the spectrum. Cadmium may replace part of mercury. The lamp may comprise as extra additions one or more of the elements scandium, yttrium, lanthanum and the lanthanides.

United- States Patent [191 Wesselink et al.

[ Dec.3, 1974 1 HALOGEN CONTAINING HIGH-PRESSURE MERCURY VAPOR DISCHARGE LAMP 751 Inventors: Gustaaf Adolf Wesselink; Hendrik Roelois, both of Emmasingel, Eindhoven, Netherlands [73] Assignee: U.S. Phillips Corporation, New

York, NY.

[22] Filed: Mar. 12, 1973 [21] Appl. No.3 340,256

[30] Foreign Application PrioritysData I Mar. 20, 1972 Netherlands 7203720 [52 U.S.Cl. ..313/228,313/229' 51 1m. c1 H01j 61/20, I-lOlj 61/22 58 Field of Search ..313/225-229 [56] References Cited UNITED STATES PATENTS Edris et all 313/229 X 3,445,719 5/1969 Thouret etal. 313/225 X 3,452,238 6/1969 Larson 313/229 3,639,801 2/1972 Jacobs et a1. 313/228 X Primary Examiner-Herman Karl Saalbach Assistant Examiner-Siegfried H. Grimm [57] ABSTRACT as extra additions one or more of the elements scan- 1 dium, yttrium, lanthanum and the lanthanides.

7 Claims, 2 Drawing Figures SHEEY 2 OF 46o 4&0 1.1.0 4&0 400 size 520 5140 5 60 5 5% 5 20 540 see 80 160 750 in nm HALOGEN CONTAINING HIGH-PRESSURE MERCURY VAPOR DISCHARGE LAMP The invention relates to a high-pressure mercury vapour discharge lamp comprising a discharge vessel whose wall is subjected to a power of between and 100 W per sq.cm during operation of the lamp. In addition to mercury and one or more rare gases the discharge vessel contains halides of given elements. In such a lamp the rare gas which has a relatively low partial pressure, for example, between 5 and 100 Torr serves as an ignition gas. At the operating temperature of the lamp the mercury vapour pressure has a value of between approximately 0.5 and atmospheres and the halides are partly evaporated and decomposed.

The addition of elements in the form of halides particularly iodides of these elements to the discharge vessel of a high-pressure mercury vapour discharge lamp is known (see, for example, U.S. Pat. No. 3,234,421) and results in a colour variation of the emitted light and an improvement of the colour rendition. In most cases the efficiency of the lamp is ,also satisfactorily influenced.

A lamp filling which is often used in practice is described in Netherlands Pat. No. 137,797 issued on Oct. 3, 1973 (see corresponding British Pat. No. 1,008,339). The lamp described in this Application not only contains a rare gas and mercury but also the iodides of sodium, thallium and indium. Sodium iodide is present in an excess in the lamp, that is to say, unevaporated sodium iodide is still present during operation of the lamp. In connection with the sodium iodide dosage in the lamp a very high excess is used in practice. The addition of iodides results in the mercury spectrum of the radiation emitted by the lamp beingsuppressed to a considerable extent. Sodium iodide provides a strong contribution in the yellow part of the spectrum. As a result of the addition of thallium and indium iodide a strong contribution in the green and blue parts, respectively, of the spectrum is obtained. A high light output and a colour rendition which is satisfactory for general uses can'be achieved with the known lamp.

l or those-uses where stringent requirements are im- 7 posed, on the rendition of colours an addition of the spectrumof the radiation emitted by the lamp is, howi ever, necessary. It has been found that particularly the intensity in the red part of the spectrum is insufficient so that a satisfactory rendition of red colours cannot be obtained. To improve this Netherlands Patent Application No. 6,603,920 published on Sept. 26, 1967 (see also corresponding British Pat. No. 1,425,063 proposes to add lithium iodide to such a lamp. By using lithium iodide, which likewise as sodium iodide is dosed in an excess, two strong emission lines atapproximately 610 and 670 nm are produced in the spectral distribution of the radiation emitted by the lamp. A great drawback of the use of lithium iodide in a high-pressure mercury vapour discharge lamp is that of the spectrum and in which the drawbacks of the use of lithium iodide do not occur. v

According to the invention a high-pressure mercury vapour discharge lamp has a discharge vessel whose wall is subjected to a power of between 10. and 100 W per sq.cm during operation of the lamp and which comprises a rare gas as an ignition gas, at least one of the halogens iodine, bromine and chlorine, from 0.5 to 40 mg of mercury per cubic cm of content of the discharge vessel, such a quantity of sodium in the form of sodium halide that unevaporated sodium halide is present during operation, from 0.25 to 25 percent by weight of thallium calculated on the quantity of mercury and from 0 to 15 percent by weight of indium calculated on the quantity of mercury, and is characterized in that the more the metals thallium and possibly indium. Under the operating conditions'of the lamp, the wall of the lamp is to be subjected to a power of between 10 and 100 W per sq. cm cm in order to ensure a wall tempera ture whichis high. enough to reach the desired vapour pressure of the halides. The quantity of mercury is to be chosen within the above-mentioned limits. If .less

than 0.5 mg of mercury per cubic cm is useda too low arc voltage is obtained so'that too little energy is taken up by the lamp. When using a mercury quantity of more than 40 mg' per cubic cm an unstable discharge is obtained. The quantity of thallium is to be at least 0.25 percent by weight calculated on the quantity of mercury because otherwise a too' low light output isobtained. When using more than 25 percent by weight of present in' the lamp in the form of calcium halide (for example, Cab) which evaporates during operation of the lamp and entirely or. partly decomposes in the disspectrum of the emitted radiation of a lamp according to the invention. This contribution originates from the calcium monohalide molecules. Furthermore atomic emission lines of calcium are found at approximately 610 and 645 nm.

The quantity of halogen in a lamp according to the invention is at least equal to the chemical equivalent of sodium and calcium present, that is to say, the quantity of halogen is sufficient to bind sodium and calcium to v NaX and CaX respectively, in which X represents one or more of the elements I, Br and Cl. It has been found that with this minimum quantity of halogen also the other metals present in the lamp, with the exception of mercury, can be introduced into the discharge in the form of halides of these elements. The maximum quantity of halogen is twice the chemical equivalent of sodium, calcium, thallium and indium present. In fact, if the lamp contains more halogen than the said maximum quantity, an unstable discharge and a low efficiency is obtained.

A lamp according to the invention has the advantage that the spectral distribution of the radiation emitted in the red part of the spectrum consists for a considerable part of a broad band. This originates from the calcium monohalide molecules. As is known such a spectral distribution has a favourable influence on the colour rendition of the lamp.

A further advantage of a lamp according to the invention is that calcium halide used is not aggressive which is in contrast with lithium iodide used in the known lamps. As a result there is substantially no attack of the wall of the lamp according to the invention and a long lifetime can be achieved with these lamps.

Lamps according to the invention are preferred in which the wall load is between 10 and 30 W per sq.cm and which contains from 0.5 to 10 mg of mercury per cubic cm from 5 to 20 percent by weight of thallium and from to 10 percent by weight of indium and in which furthermore the quantity of calcium is between and 20 percent by weight. The highest light outputs and optimum results as regards the colour rendition are achieved with such lamps.

A lamp according to the invention has the advantage that the location in the spectrum of the emission band of calcium monohalide can be influenced by suitable choice of the halogen to be used. For CaIthis band is located between approximately 630 and 670 nm, for CaBr between approximately 610 and 640 nm and for CaCl between approximatey 605 and 640 nm. In a preferred embodiment of a lamp according to the invention iodine is used as a halogen because bromine and chlorine may give rise to, for example, electrode at tack.

In a lamp according to the invention up to 50 percent by weight of the quantity of mercury may be advantageously replaced by cadmium. Likewise as mercury, cadmium has the function of a buffer gas. Furthermore cadmium gives rise to a desirable extra contribution to the light emission in the green and green-blue parts of the spectrum.

' In an advantageous embodiment of a lamp according to the invention the discharge vessel furthermore comprises one or more of the elements scandium, yttrium, lanthanum and the lanthanides in a quantity of between 0.l and 40 percent by weight calculated relative to mercury. The quantity of halogen is chosen between the quantity which is chemically equivalent to sodium, calcium, scandium, yttrium, lanthanum and the lanthanides present and twice the quantity which is chemically equivalent to all metals present, with the exception of mercury and cadmium. The addition of the said extra elements has the advantage that in the spectrum of the radiation emitted by the lamp a desired addition is obtained particularly in the range between 400 and 530 nm. If one or more of the said extra elements are added to the lamp, indium may be completely omitted in the lamp filling while yet obtaining a sufficient contribution in the blue part of the spectrum. The omission of indium has the further advantage that generally higher light outputs are obtained.

A lamp according to the invention preferably comprises as an extra element neodymium in a quantity of between 3 and 40 percent by weight of the quantity of mercury. The extra contribution provided by neodymium to the spectrum of the radiation emitted by the lamp consists of a large number of lines. Especially in the green-blue part of the spectrum these lines constitute a quasi-continuous radiation contribution so that the colour rendition of the lamp is still further improved.

In a further preferred embodiment of a lamp according to the invention dysprosium (possibly in combination with neodymium) is present as an extra element in a quantity of between 3 and 40 percent by weight (calculated relative to mercury). Dysprosium likewise provides a quasi-continuous contribution and this in substantially the entire visible part of the spectrum so that the colour rendition of the lamp is favourably influenced. v

The invention will now be described in greater detail with reference to a drawing and a number of embodiments. In the drawing FIG. 1 shows a lamp according to the invention and FIG. 2 shows in a graph the spectral distribution of the emitted radiation of a lamp according to the invention.

In FIG. 1, l is a quartz glass discharge vessel of a lamp according to the invention which has a power output of approximately 400 Watts during operation. Pinches 2 and 3 in which current supply elements 4 and 5 have been sealed are formed at both ends of the discharge vessel I. These current supply elements are connected within the discharge vessel to tungsten electrodes 6 and 7 between which the discharge takes place during operation. The discharge vessel 1 is placed in an evacuated or inert gas-filled outer envelope 8, for example, of hard glass which has a pinch 9 at one end through which current supply wires 10 and 11 have been passed in a vacuum-tight manner. The current supply wires 10 and 11 are connected to the current supply elements 4 and 5 and also serve as supporting terminals for the discharge vessel. The discharge vessel I 1 has an internal diameter of 15.5 mm and a content of 7.5 cubic cm. The distance between the electrodes is 41 mm.

EXAMPLE I The discharge vessel of a lamp according to FIG. 1 is filled with 35 mg Hg 0.20 Nal mol 7.5 mg Tl l.7 mg In 0. l6 Cal, mol

and furthermore with a mixture of neon and 1 percent of argon up to a pressure of 40 Torr.

A light output '1 of 56 lm/W and a colour temperature T of the emitted radiation of 5350 K were measured on this lamp. In order to determine the colour rendition quality of the lamp the colour rendering indices were measured (see ClE Publication No. 13 (E- l.3.2.), 1965). The values for Rhd a8 and R (mean value of the colour rendering index for 8 and 14 test colours, respectively) were 75 and 63, respectively. For the purpose of comparison the values of colour temperature and colour rendering index of a completely analogous lamp which does not contain Cal were measured. These values were: T 4200 K and R 8 68.5 and RG14 7 Example 2. A lamp as shown in FIG. 1 was provided with 28 mg Hg 0.22 Nal mol 5.2 mg Tl 2 mg In 0.18 Cal: mol 10 mg Cd and furthermore with a mixture of neon and 1 percent of argon up to a pressure of 40 Torr.

Measured: 1) 58 lm/W T 4650 K R =85.5 R =78 I EXAMPLE 3 A lamp as shown in FIG. 1 was provided with 36 mg Hg 0.08 Nal mol 2.5 mg Tl 0.08 Cal,

mol 0.03 Gd: mol

and furthermore with a mixture of neon and 1 percent of argon up to a pressure of 20 Torr.

Measured: 1 78 lrn/W T 4950 K T R,, 83.5 R 75.5.

EXAMPLE 4 A lamp as showri in FIG. 1 was provided with mg Hg 0.08 Na] mol 4.5 mg Tl l.5 mg' In 0.08 Cal,

mol 0,03 DyJ mol and furthermore with argon up to a pressure of 20 Torr.

Measured: v RG14:

' EXAMPLE A lamp as shown in FIG. 1 was filled with v 36 mg Hg 0.08 Nal mol 5 mg Tl 1.7 mg In 0.08 Cal mol 10 0.03 Ndl mol and furthermore with a mixture of neon and 1 percent of argon up to a pressure of 40 Torr. l5

Measured:

The spectral energy distribution of the radiation emitted by this lamp is shown in the drawing of FIG. 2. In the Figure the wavelength A is plotted in nm onthe horizontal axis. The emitted radiation energy E per wavelength interval of 5 nm is plotted in arbitrary units on the vertical axis.

EXAMPLE 6 A lamp as shown in FIG. 1 was provided with 24 mg Hg 0.l NaI mol 5 mg Tl I mg ln l0 mg ca- 0.l Cal,

mol 0.05- DyI,

mol 0.05 'Ndl mol and furthermore with a'mixture of neon and 1 percent of argon up to a pressure of 40 Torr.

and furthermore with-argon up to a pressure of 20 Torr.

Results: 1; 65 lm/W T 5200 K an un EXAMPLE 8 A lamp as shown in FIG. 1 was provided with 28 mg Hg 5.2 mg Ti 2 mg In 0.I6 CaCl mol and furthermore with argon up to a pressure of 20 Torr.

Measured: T 5150 K What is claimed is:

l. A high-pressure mercury vapour discharge lamp comprising a discharge vessel whose wall is subjected to a power of between 10 and 100 W per sq.cm. during operation of the lamp and consisting of a rare gas as an ignition gas, at least one of the halogens iodine, bromine and chlorine, from 0.5 to 40 mg of mercury per cubic cm of content of the discharge vessel, such a quantity of sodium in the form of sodium halide that unevaporated sodium halide is present during operation, from 0.25 to 25 percent by weight of thallium calculated on the quantity of mercury and from 0 to percent by weight of indium calculated on the quantity of mercury, wherein the discharge vessel furthermore contains calcium in a quantity of between 1 and 30 percent by weight of the quantity of mercury and that the quantity of halogen is at least equal to the chemical equivalent of sodium and calcium present and is not more than twice the chemical equivalent of sodium, calcium, thallium and indium present.

2. A high-pressure mercury vapour discharge lamp as claimed in claim 1 in which the wall load is between 10 and 30 W per sq.cm and comprising from 0.5 to 10 mg of mercury per cubic cm of content of the discharge vessel, from 5 to 20 percent by weight of thallium and from 0 to 10 percent by weight of indium calculated on the quantity of mercury, and wherein the discharge vessel contains calcium in a quantity of between 5 and 20 percent by weight of the quantity of mercury.

3. A high-pressure mercury vapour discharge lamp as claimed in claim 1, wherein the halogen is iodine.

4. A high-pressure mercury vapour discharge lamp as claimed in claim 1, wherein up to 50 percent by weight of mercury is replaced by cadmium.

5. A high-pressure mercury vapour discharge lamp as claimed in claim 1, wherein the discharge vessel furthermore contains one or more of the elements scandium, yttrium, lanthanum and the lanthanides in a quantity of between 0.1 and 40 percent by weight of the quantity of mercury and that the quantity of halogen is at least equal to the chemical equivalent of sodium, calcium, scandium, yttrium, lanthanum and the lanthanides present and is not more than twice the chemical equivalent of all metals present, with the exception of mercury and cadmium.

6. A high-pressure mercury vapour discharge lamp as claimed in claim 5, wherein the discharge vessel contains neodymium in a quantity of between 3 and 40 percent by weight of the quantity of mercury.

7. A high-pressure mercury vapour discharge lamp as claimed in claim 5, wherein the discharge vessel contains dysprosium in a quantity of between 3 and 40 percent by weight of the quantity of mercury.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,852,630

DATED December 3, 1974 |NVENTOR(S) GUSTAAF ADOLF WESSELINK ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line 31 delete "consisting of";

line 32 after "halogens" insert -from the group consisting of.

Signed and Scaled this Twenty-fifth Day Of January 1977 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (nmmissioner ufPalems and Trademarks mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,852,630 Dated December 3, 1974 Inventor-(s) Gustaaf Adolf Wesselink; Hendrik Roelofs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

. '1 Col. 1, line 52, change "1,425,063" to -l,l25,063-

Col. 2, line 30, delete "cm" second occurrence;

1 Col. 4, line 58, change "0.20 NaI" mol to: -0.20 mmol NaI- Col. 4, line 62, change 0.16 CaI mol to: O.l6 mmol CaI Col. 5, line 3, delete "Rhd a8" and insert Ra8- Col. 5, line 16, change "0.22 NaI" mol to: -0.22 mmol NaI- Col. 5, line 19, change "0.18 CaI mol to: O.l8 mmol CaI Col. 5, line 36, change "0.08 NaI" mol l to: 0.08 mmol NaI- Patent No.

Inventor-(s) Gusta af Adolf Wesselink; Hendrik Roelofs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 2 Dated line line

line

line

line

line

mol

to: --0.08 mmol CaI change "0.03

mol

to: -0.03 mmol DyJ change "0.08 NaI" mol -0.08 mmcl NaI- December 3, 1974 Page 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,852,630 Dated December 3, 1974 Inventor(s) Gustaaf Adolf Wesselink; Hendrik Roelofs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 6, line 9, change "0.08 CaI mol 1 to: -0.08 mmol CaI Col. 6, line 11, change "0.03 NdI mol to: ---0.03 mmol NdI Col. 6, line 36, change "0.1 NaI" mol to: --0.1 mmol NaI-"- Col. 6, line 41, change "0.1 CaI mol to: ---0.1 mmol CaI Col. 6, line 43, change "0.05 DYI mol to: --0.05 mmol DyI Col. 6, line 44, change "0.05 No.1

mol

to: --0.05 mmol NdI Page 4 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION t Patent NO- 3,852,630 I Dated December 3, 1974 Inventor(s) Gustaaf Adolf Wesselink; Hendrik Roelofs It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 6, line 63, change "0.22 NaI"' mol to: -0.22 mmol NaI- Col. 6, line 65, change "0.2 I CaBr mol to: --O.2 mmol CaBr Col. 7, line 14, change "0.22 NaI" mol to: --0.22 mmol NaI- Col. 7, line 18, change "0.16 CaCl mol to: --O.l6 mmol CaCl Signed and Scaled this ninth Day of December 1975 '[SEAL] Atlest.

. RUTH C. MASON C. MARSHALL DANN Arrestin ff Commissioner ofPatents and Trademarks 

1. A HIGH-PRESSURE MERCURY VAPOR DISCHARGE LAMP COMPRISING A DISCHARGE VESSEL WHOSE WALL IS SUBJECTED TO A POWER OF BETWEEN 10 AND 100 W PER SQ.CM. DURING OPERATION OF THE LAMP AND CONSISTING OF A RARE GAS AS AN IGNITION GAS, AT LEAST O NE OF THE HALOGENS IODINE, BROMINE AND CHLORINE, FROM 0.5 TO 40 MG OF MERCURY PE CUBIC CM OF CONTENT OF THE DISCHARGE VESSEL, SUCH A QUANTITY OF SODIUM IN THE FORM OF SODIUM HALIDE THAT UNEVAPORATED SODIUM HALIDE IS PRESENT DURING OPERATION, FROM 0.25 TO 25 PERCENT BY WEIGHT OF THALLIUM CALCULATED ON THE QUANTITY OF MERCURY AND FROM 0 TO 15 PERCENT BY WEIGHT OF INDIUM CALCULATED ON THE QUANTITY OF MERCURY, WHEREIN THE DISCHARGE VESSEL FURTHERMORE CONTAINS CALCIUM IN A QUANTITY OF BETWEEN 1 AND 30 PERCENT BY WEIGHT OF THE QUANTITY OF MERCURY AND THAT THE QUANTITY OF HALOGEN IS AT LEAST EQUAL TO THE CHEMICAL EQUIVALENT OF SODIUM AND CALCIUM PRESENT AND IS NOT MORE THAN TWICE THE CHEMICAL EQUIVALENT OF SODIUM, CALCIUM, THALLIUM AND INDIUM PRESENT.
 2. A high-pressure mercury vapour discharge lamp as claimed in claim 1 in which the wall load is between 10 and 30 W per sq.cm and comprising from 0.5 to 10 mg of mercury per cubic cm of content of the discharge vessel, from 5 to 20 percent by weight of thallium and from 0 to 10 percent by weight of indium calculated on the quantity of mercury, and wherein the discharge vessel contains calcium in a quantity of between 5 and 20 percent by weight of the quantity of mercury.
 3. A high-pressure mercury vapour discharge lamp as claimed in claim 1, wherein the halogen is iodine.
 4. A high-pressure mercury vapour discharge lamp as claimed in claim 1, wherein up to 50 percent by weight of mercury is replaced by cadmium.
 5. A high-pressure mercury vapour discharge lamp as claimed in claim 1, wherein the discharge vessel furthermore contains one or more of the elements scandium, yttrium, lanthanum and the lanthanides in a quantity of between 0.1 and 40 percent by weight of the quantity of mercury and that the quantity of halogen is at least equal to the chemical equivalent of sodium, calcium, scandium, yttrium, lanthanum and the lanthanides present and is not more than twice the chemical equivalent of all metals present, with the exception of mercury and cadmium.
 6. A high-pressure mercury vapour discharge lamp as claimed in claim 5, wherein the discharge vessel contains neodymium in a quantity of between 3 and 40 percent by weight of the quantity of mercury.
 7. A high-pressure mercury vapour discharge lamp as claimed in claim 5, wherein the discharge vessel contains dysprosium in a quantity of between 3 and 40 percent by weight of the quantity of mercury. 